LED flashlight with battery life indicator

Abstract

A flashlight includes a light powered by a battery, and a circuit having: a memory for storing a battery life information and voltage output information versus time for the battery to power the light, a controller operating a count down timer to accumulate an amount of time that the battery powers the light, a voltage measure circuit for monitoring the voltage output by the battery while the battery powers the light and supply the voltage output to the controller. The controller determines: a first remaining battery life by comparing the accumulated time to the battery life, a second remaining battery life by comparing the voltage output to the voltage output information, and the lesser of the first and second remaining battery lives. The flashlight includes a display for receiving a command from the controller to display the lesser of the first remaining battery life and the second remaining battery life.

What is claimed is: 
     
       1. A circuit configured for use in a portable electronic device, which is configured to be powered by a battery, the circuit comprising:
 a memory configured to store battery life information for the battery, wherein the battery life information includes a battery life of the battery and includes voltage output information of the battery over a time of use of the battery to power the portable electronic device; 
 a controller coupled to the memory and configured to receive the battery life information from the memory and to operate as a count down timer to accumulate an amount of time that the battery provides power to the portable electronic device; 
 a voltage measure circuit coupled to the controller and configured to monitor the voltage output by the battery while the battery provides power to the portable electronic device to power the portable electronic device and to supply voltage information for the voltage output to the controller; 
 wherein the controller is configured to i) determine a first remaining battery life for the battery via comparison of the accumulated time to the battery life, ii) determine a second remaining battery life via comparison of the supplied voltage information from the voltage measure circuit to the voltage output information of the battery over time, and iii) determine the lesser of the first remaining battery life and the second remaining battery life; and 
 a display coupled to the controller and configured to receive a command from the controller to display the lesser of the first remaining battery life and the second remaining battery life. 
 
     
     
       2. The circuit of  claim 1 , wherein the display is configured to display the lesser of the first remaining battery life and the second remaining battery life in an hours and minutes format. 
     
     
       3. The circuit of  claim 1 , wherein the display is configured to display a plurality of colors and the colors indicate different percentages of remaining battery life of the battery. 
     
     
       4. The circuit of  claim 3 , wherein the plurality of colors includes green, yellow, orange, and red. 
     
     
       5. The circuit of  claim 1 , further comprising a temperature sensor disposed in a battery compartment and coupled to the controller, wherein the temperature sensor is configured to detect the temperature of the battery, and the controller is configured to receive temperature information from the temperature sensor and adjust the first remaining battery life based on the temperature information. 
     
     
       6. The circuit of  claim 1 , wherein the controller is configured to decrease the first remaining battery life to the second remaining battery life if the second remaining battery life is less than the first remaining battery life. 
     
     
       7. A portable electronic device configured to be powered by a battery, the portable electronic device comprising:
 a memory configured to store battery life information for the battery, wherein the battery life information includes a battery life of the battery and includes voltage output information of the battery over a time of use of the battery to power the portable electronic device, 
 a controller coupled to the memory and configured to receive the battery life information from the memory and to operate as a count down timer to accumulate an amount of time that the battery provides power to power the portable electronic device; 
 a voltage measure circuit configured to monitor the voltage output by the battery while the battery provides power to power the portable electronic device and to supply voltage information for the voltage to the controller; 
 wherein the controller is configured to i) determine a first remaining battery life for the battery via comparison of the accumulated time to the battery life, ii) determine a second remaining battery life via comparison of the supplied voltage information from the voltage measure circuit to the voltage output information of the battery over time, and iii) determine the lesser of the first remaining battery life and the second remaining battery life; and 
 a display coupled to the controller and configured to receive a command from the controller to display the lesser of the first remaining battery life and the second remaining battery life. 
 
     
     
       8. The portable electronic device of  claim 7 , further comprising a closed loop control circuit configured to provide a substantially constant delivery of average current through a light emitting device via closed loop control, wherein the closed loop control circuit is configured to compare a predetermined set point for current for a plurality of battery life discharge profiles versus measured variable current scaled and delivered to the microcontroller via the closed loop control circuit. 
     
     
       9. The portable electronic device of  claim 7 , wherein the display is configured to display the lesser of the first remaining battery life and the second remaining battery life in an hours and minutes format. 
     
     
       10. The portable electronic device of  claim 7 , wherein the display is configured to display a plurality of colors and the colors indicate different percentages of remaining battery life of the battery. 
     
     
       11. The portable electronic device of  claim 7 , wherein the controller is configured to decrease the first remaining battery life to the second remaining battery life if the second remaining battery life is less than the first remaining battery life.